This invention relates to the field of polymer blends.
Blends of polystyrene and polypropylene are known in the art. U.S. Pat. No. 3,018,263 describes blends of crystalline polypropylene with from 5-25% polystyrene. U.S. Pat. No. 3,092,891 discloses the manufacture of monofilaments from mixtures of polypropylene and polystyrene in ratios of from 8:2 to 9.8:0.2. U.S. Pat. No. 3,173,163 describes a longitudinally oriented filament or bristle which is melt extruded from a mixture of from 5-95% of a polyolefin such as polypropylene with the balance made up of an incompatible resin such as polystyrene. U.S. Pat. No. 3,652,725 relates to extrusion coating compositions which are based on triblends of polyethylene, crystalline polypropylene and toluene-alpha-methyl styrene copolymer. U.S. Pat. No. 3,666,834 describes the fabrication of oriented film based on blends of polypropylene and poly(para-tertiary-butyl styrene). In the polymer blend disclosed in U.S. Pat. No. 3,875,260, ethylene-propylene terpolymer particles are contained within a matrix of polystyrene. U.S. Pat. No. 4,183,845 discloses melt-extrudable blends of polypropylene/polystyrene in a ratio of 5:1 to 2:1. The polymer blends of U.S. Pat. No. 4,255,531 are made up of poly(p-methylstyrene) with from 0.1-10% of a poly(C.sub.2-4) olefin such as polypropylene homopolymer or copolymer. U.S. Pat. No. 4,237,190 describes melt extrudable polypropylene/polystyrene blends in the range of 5:1 to 2:1. In U.S. Pat. No. 4,365,044, polymer triblends are prepared with a crystalline polypropylene, a hydrogenated copolymer of vinyl toluene and alpha-methyl styrene and a low density polyethylene. U.S. Pat. No. 4,394,235 provides blends of polypropylene and styrene-terpene copolymers for fabricating packaging films.